Table 1.

Values of probabilities used at various chance nodes in decision tree^*†

Chance node	Absolute annual risk, % (95% CI)
Risk of having a thromboembolic event (stroke) among patients with untreated atrial fibrillation1,11,12,13
Age 65-75 yr
No risk factor	4.3 (2.7-7.1)
≥1 risk factor	5.7 (3.9-8.3)
Congestive cardiac failure, no risk factor	8.4 (2.1-33.0)
Congestive cardiac failure, ≥1 risk factor	11.7 (5.3-26.0)
Age > 75 yr
No risk factor	3.5 (3.5-26.0)
≥1 risk factor	8.1 (4.7-13.9)
Congestive cardiac failure, no risk factor	10.9 (1.4-78.0)
Congestive cardiac failure, ≥1 risk factor	19.7 (7.4-52.0)
Previous cardiovascular accident or TIA	12.0‡
Relative risk reduction when treated with warfarin sodium1
Annual risk reduction, %	68
Probability of outcome after thromboembolic event (stroke)14
Affected (functionally dependent)	35 (30.0-39.0)
Unaffected (functionally independent)	65 (61.0-70.0)
Probability of side effects with warfarin treatment15
Minor side effect	11.8 (8.8-16.0)
Major side effect	1.1 (0.5-1.5)
Any side effect	12.9‡
Risk factor = diabetes mellitus or hypertension (but not congestive cardiac failure).
CI = confidence interval; TIA = transient ischemic attack.

^*Superscript numbers indicate reference citations.

^†See figure 2.

^‡Confidence interval not given.